The present invention relates generally to wireless networks and more particularly to LTE downlink scheduling.
Long-term evolution LTE downlink scheduling with multiple-input multiple-output MIMO encompasses several practical constraints such as equal power allocation, common MIMO mode, maximum number of scheduled users. Most researchers who studied downlink DL scheduling only considered single-input single-output SISO scheduling and most of them did not consider the foregoing mentioned practical constraints.
Of particular interest is the common MIMO mode, which requires that a common MIMO mode (such as the precoding matrix, rank) should be employed across all resource blocks RBs allocated to a given user. Moreover, if the rank of the precoding matrix is at least two, two codewords are used and each codeword is assigned with one modulation-and-coding scheme MCS.
A few recent works considered some of the constraints this invention considers, but not all of them. One prior art work considered the scheduling problem with finite queue but only SISO was considered. Another prior work studied the MIMO scheduling but did not consider other constraints (such as finite queue, user limit, etc). And their algorithms only support two possible MIMO modes (transmit diversity and spatial Multiplexing) while we consider the number of streams as the MIMO modes, which can be more than 2. Another prior effort considered the common MCS constraint but only for SISO and only a greedy solution without performance guarantee was proposed.
Accordingly, there is a need for a method for LTE downlink scheduling with MIMO that overcomes the limitations of prior efforts.